Thank you Uli, Vixy, AJmeow, Lynne, Silver Mom, Jadelover, GS, ms Oinky, Tiffins, Claire for your feedback!
I wanted a small oval bangle and based the measurement on Algae (my tiniest) but because I don't have calipers, my measurements were probably off. Not Allan's fault. The oval turned out too "round" and not flat enough hence it doesn't sit as snug. Width is ok, I asked for 12-13mm. Allan's final oval is a wee bit larger on all sides too. If I order another bangle, I will probably get a princess in 49-50mm to be safe.